Cytotoxic and Antimicrobial Activities of the Constituents of Ten Plant Species from Tanzania

Abstract

This paper reports on the antimicrobial and cytotoxicity activities of crude extracts from the plant species Clemaptosis scabiosifolia (Ranunculaceae), Diospyros mafiensis (Ebenaceae), Dolichos kilimandscharicus (Leguminosae), Gnidia kraussiana (Thymelaeaceae), Hugonia castaneifolia (Linaceae), Neorautanenia mitis (Pappilionaceae), Tagetes minuta (Asteraceae), Uvaria acuminata (Annonaceae), Vernonia amygdalina (Asteraceae) and Zanha africana (Sapindaceae). All crude extracts were screened for their cytotoxicities in the brine shrimp lethality test (BST). Fractions and pure compounds from Hugonia castaneifolia, Diospyros mafiensis and Uvaria acuminata were tested for their cytotoxicity and antimicrobial activities against ten microorganisms, namely Candida albicans, Bacillus anthracis, Escherichia coli, Klebsiela pneumoniae, Proteus sp., Pseudomonas aeruginosa, Salmonella typhimurium, Shigella boydii, Staphyloccus aureus, and Vibrio cholerae. Of all the tested crude samples, extracts from Neorautanenia mitis had the highest cytotoxicity, having LC₅₀ values of 0.12, 0.65, 1.54 and 2.33 µg/mL for pet ether, dichloromethane, ethanol and methanol/chloroform (1:1 v/v) extracts, respectively. The mixture of uvaretin (2) and diuvaretin (3) isolated from Uvaria acuminata had the highest cytotoxicity (LC₅₀ = 3.59 µg/mL). Furthermore, the mixture of uvaretin (2) and diuvaretin (3) was active against the Gram-positive bacteria S. aureus and B. anthracis, being 65% and 57% as active as the standard antibacterial drug, gentamycin, against the two bacteria species, respectively.

Keywords: Artemia salina, Candida albicans, Gram-Negative Bacteria, Gram-Positive Bacteria